"An hallucination is a strictly sensational form of consciousness, as good and true a sensation as if there were a real object there. The object happens to be not there, that is all."

- Wiliam James

People hallucinate for a lot of different reasons, and neurologist Oliver Sacks explores a number of them in this book. Hallucinations can signify a neurological condition (Parkinson's, migraine, epilepsy, narcolepsy), fill an absence (blindness, deafness, intentional sensory deprivation), or be brought on by other experiences (fever, drug use, psychological trauma). Sacks covers each of these with his characteristic compassion and humor.

The hallmarks of a Sacks book are all here, from the fascinating case studies to the rambling footnotes; from the incisive personal anecdotes to the extraordinary glimpses into the workings of our own cerebral hardware.

While this book isn't as thoroughly fascinating as The Man Who Mistook His Wife For A Hat or Musicophilia, it's worth a read if only for the chapter on drug use. After discussing historical references to altered states and delving a bit into the mechanics of a drug trip, Sacks launches into stories about his own experiences in this vein. They're bizarre and darkly hilarious.

For instance, he recounts once deliberately taking a cocktail of amphetamines, LSD, and cannabis for the express purpose of experiencing the color indigo (for reasons that probably made sense in the 60's). "About twenty minutes after taking this, I faced a white wall and exclaimed, 'I want to see indigo now -- now!'" And sure enough indigo appears, there on the wall.

Fully enraptured, he proceeds to spend the next several months trying to find the color again, but he only catches a glimpse of it once, shining through some ancient Egyptian jewelry in a museum. And never again after that.

In another incident, Sacks shoots himself up with multiple vials of morphine and ends up staring at a painting of Napoleon for what felt like a few minutes, only to turn to the clock and realize it had been twelve hours.

Finally, at one point while out of his mind on hallucinogenic morning glory seeds, he accuses a visiting psychoanalyst friend of being a decoy, a realistic replica of herself. Once he's sobered up, she tells him (in true shrink fashion) that his delusion had been "a complex form of defense, a dissociation which could only be called psychotic." Sacks disagrees, and instead "maintained that my seeing her as a duplicate or impostor was neurological in origin, a disconnection between perception and feelings." The friend wins the argument by pointing out that "whatever view was correct, taking mind-altering drugs every weekend, alone, and in high doses, surely testified to some intense inner needs or conflicts, and that I should explore these with a therapist."

TOUCHÉ.

While autobiographical anecdotes are common in Sacks's books, I'd never pictured him as a young acid head with a singularly methodical, scientific approach to tripping balls. It's oddly endearing. In any case, it is while high on amphetamines that he decides to write neurological literature in the first place, and so here we are.

The rest of the book is somewhat hit-or-miss, some chapters more interesting than others, but overall it's an interesting look at some of the varieties of hallucinations, their neurological foundations and their subjective manifestations - from euphoric to terrifying, from sacred to meaningless.

(On a personal note, the only significant hallucination I remember experiencing was when I was about six or eight years old. I had a giant Raggedy Ann doll that was as tall as I was, and she sat on top of a bookshelf about eye level across the room from my top-bunk bed. One night, while trying to get to sleep, I remember looking over at her and she was sitting there swinging her legs - slowly, deliberately, one after the other, all the way up and all the way down. With her frozen cloth grin gazing at me out of the gloom, it was the most unsettling, terrifying thing I have ever seen.

Even as young as I was, some part of me knew it wasn't real, but I still threw that fucking doll into the back of the closet the next morning. Just thinking of it still freaks me out.)